Optical measurement instrument and optical measurement method

ABSTRACT

In order to provide an optical measurement system and an optical measurement method which is suitable for optically measuring a body to be inspected and easily obtaining an image of a desired item based on information obtained by the measurement, an optical measurement method comprising an initial display process for selectively instructing any one of selection of optical measurement, analysis of said optical measurement result and completion of a program (S 1 ); a process for inputting items of condition including a measurement mode (S 2 ); a process for displaying a light irradiation position and a light detection position and a state expressing measurement position relationship together with said mode (S 4 ); a process for instructing to form a file for storing said optical measurement result; a process for instructing a measurement condition to detect light signals from the inside of a body to be inspected which is irradiated by a multi-wavelength multi-channel (S 10 ); and a process for displaying said signals for each channel detected according to said instructed result (S 11 ).

This application is a continuation of U.S. application Ser. No.09/674,008, filed Oct. 24, 2000, which is a PCT National StageApplication of PCT/JP99/02207, filed Apr. 26, 1999, which claimspriority from Japanese Patent Application 10-134649, filed Apr. 28,1998, the entirety of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to an optical measurement system and anoptical measurement method, and particularly, to an optical measurementsystem which is suitable for optically measuring the inside of abiological body and imaging the inside of the biological body based oninformation signals obtained by the measurement.

A technology of easily measuring the inside of a biological body withoutaffecting any ill effect on the biological body is desired in the fieldof clinical treatment. Measurement using light is very effective forthis desire. The first reason is that oxygen metabolism inside thebiological body corresponds to a concentration of specific pigments(hemoglobin, cytochrome a a3, myoglobin and so on), that is, lightabsorbents in the biological body, and the concentration of the pigmentscan be obtained from an amount of absorbed light (in a wavelength bandfrom visible light to near-infrared light). The second reason is thatlight can be easily handled using an optical fiber.

Systems making use of the advantage of biological measurement usinglight are disclosed, for example, in Japanese Patent ApplicationLaid-Open No. 63-277038, in Japanese Patent Application Laid-Open No.5300887 and so on. In the systems, light having wavelengths from visuallight to near-infrared light is irradiated onto a biological body, andan inside of a biological body is measured from the reflected lightdetected at a position 10 to 50 mm distant from the irradiated position.Further, systems for measuring a CT image of oxygen metabolism fromlight transmitted a biological body having a thickness of 100 to 200 mm,that is, optical CT systems are disclosed, for example, in JapanesePatent Application Laid-Open No. 60-72542 and in Japanese PatentApplication Laid-Open No. 62-231625.

In regard to clinical application of biological body opticalmeasurement, in a case of measuring, for example, a head there aremeasurement of an activation state of cerebral oxygen metabolism andmeasurement of a local cerebral hemorrhage. In regard to cerebral oxygenmetabolism, it is possible to measure higher order brain functions frommotion, senses to thinking. In such measurement, the effect of themeasurement can be increased larger by displaying the measured result asan image than by not displaying any image. For example, measurement anddisplay as an image is indispensable for detecting a portion whereoxygen metabolism is locally changed.

In a multichannel optical measurement system, it is difficult to speedydetect a channel having a problem unless correspondence between actualmeasured positions and measured signals is shown to an operatoroperating the system.

In addition, there have been problems to cause serious results in thefield of clinical treatment unless the operator inputs a large amount ofmeasuring conditions before initiating the measurement.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an optical measurementsystem and an optical measurement method which is suitable for opticallymeasuring a body to be inspected and easily obtaining an image of adesired item based on information obtained by the measurement.

In order to attain the above object, in the present invention, measuringpositions and a layout of optical fibers specific in the multi-channeloptical measurement system are presented to an operator using a displayportion. Further, by adding a function of changing the displayed layoutcorresponding to a measuring signal, it becomes easy to understand thestatus of the channels. Furthermore, in the present invention, a limitednumber of windows for inputting measurement conditions are displayed onthe display portion, and measurement conditions in the next levelhierarchy are displayed after completion of the inputting.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing the construction of the main portionof an embodiment of an optical measurement system to which the presentinvention is applied.

FIG. 2 is a flowchart showing an example of processing flow inaccordance with the present invention for measuring a body to beinspected using the optical measurement system shown in FIG. 1.

FIG. 3 is a view showing an initial window which is shown on a displayportion.

FIG. 4 is a view showing a window for inputting conditions which isshown on tne display portion.

FIG. 5 is a view showing a window for displaying gain adjusting underwaywhich is shown on the display portion.

FIG. 6 is a view showing a window for displaying measured positionswhich is shown on the display portion.

FIG. 7 is a view showing a window for display abnormality which is shownon the display portion.

FIG. 8 is a view showing a window for forming a file which is shown onthe display portion.

FIG. 9 is a view showing a window for forming a directory which is shownon the display portion.

FIG. 10 is a view showing a measurement window which is shown on thedisplay portion.

FIG. 11 is a view showing a sub-menu window of Info of FIG. 10 which isshown on the display portion.

FIG. 12 is a view showing a window for inputting measurement conditionsand display conditions which is shown on the display portion.

FIG. 13 is a view showing a window of Option of FIG. 10 which is shownon the display portion.

FIG. 14 is a view showing a window for displaying a measurement datatime sequence which is shown on the display portion.

FIG. 15 is a view showing a window for inputting the display conditionsof graph of FIG. 14 which is shown on the display portion.

FIG. 16 is a view showing a window for inputting a file backup conditionwhich is shown on the display portion.

FIG. 17 is a view showing a window for input setting of the othermeasurement equipment output signal which is shown on the displayportion.

FIG. 18 is a view showing a window for setting a rectangular wave outputsignal which is shown in the display portion.

FIG. 19 is a chart showing the rectangular wave output signals of whichthe conditions are set in FIG. 18.

FIG. 20 is a view showing a window for setting an external input triggersynchronous measurement condition which is shown on the display portion.

FIG. 21 is a view showing a window for setting a measured data acquiringcondition which is shown on the display portion.

FIG. 22 is a view showing a window for checking a measured signal whichis shown on the display portion.

FIG. 23 is a block diagram showing the construction inside the lightmodule of FIG. 1.

FIG. 24 is a view showing an example of a geographical arrangement ofirradiation positions and detecting positions on a surface of a body tobe inspected.

FIG. 25 is a block diagram showing the construction of lock-in amplifiermodule of FIG. 1.

FIG. 26 is a graph showing an example of time variation of a measuredsignal at a detecting position and time variation of a predicted no-loadsignal obtained from the measured signal.

FIG. 27 is a graph showing an example of time variation of an amount ofrelative change in concentrations of oxygenated hemoglobin anddeoxygenated hemoglobin at a measurement position.

FIG. 28 is a view showing a contour image (a topography image) producedfrom time variation of an amount of relative change in a concentrationof oxygenated hemoglobin at each measurement position when motion ofleft-hand fingers of a person to be inspected is used as a load.

FIG. 29 is a view showing a contour image (a topography image) producedfrom time variation of an amount of relative change in a concentrationof oxygenated hemoglobin at each measurement position when motion ofright-hand fingers of a person to be inspected is used as a load.

FIG. 30 is a view showing an example of a display superposing atopography image on a cerebrum surface image of a person to beinspected.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 is a block diagram showing the construction of the main portionof an embodiment of an optical measurement system to which the presentinvention is applied. The present embodiment is that light isirradiated, for example, on the skin of a head and then lightpenetrating into and scattered by the body is detected from the skin toimage the inside of the cerebrum. In the embodiment, number ofmeasurement channels, that is, number of measurement positions is 12. Ofcourse, the object to be measured is not limited to a head, and thepresent invention can be applied to the other portions and to an objectother than a biological body.

A light source portion 1 is composed of four light modules 2. Each ofthe light modules is composed of a plurality of semiconductor laserseach emitting light having a different wavelength within a wavelengthband from visual to infrared, for example, two semiconductor lasers eachemitting light having either of 780 nm or 830 nm wavelength. Thesevalues of two wavelengths are not limited to 780 nm and 830 nm, andnumber of wavelengths is not limited to two. In regard to the lightsource portion 1, light emitting diodes may be used instead of thesemiconductor lasers. The light from all of the eight semiconductorlasers contained in the light source portion 1 is modulated by a.oscillating portion 3 composed of eight oscillators having differentoscillation frequency, respectively.

FIG. 23 shows the construction inside the light module 2 by taking thelight module 2(1) as an example. Semiconductor lasers 3(1-a), 3(1-b) anddrive circuits 4(1-a), 4(1-b) for the semiconductor lasers are containedin the light module 2(1). Therein, in regard to the characters in theparentheses, the numeral indicates the number of the light modulecontaining the semiconductor laser or the semiconductor laser drivecircuit, and the characters a and b indicate for wavelengths 780 nm and830 nm, respectively. The semiconductor laser drive circuits 4(1-a),4(1-b) apply direct current bias current to the semiconductor lasers3(1-a), 3(1-b), and also apply voltages having frequencies f(1-a),f(1-b) different from each other to the oscillators 3, respectively, tomodulate light beams emitted from the semiconductor lasers 3(1-a),3(1-b). The modulation in the present embodiment is analogue modulationusing sinusoidal waves, but of course, digital modulation usingrectangular waves having time intervals different from each other may beused. Each of the light beams modulated as described above is introducedinto each of optical fibers 6 through each of condenser lenses 5 foreach of the semiconductor lasers. Each of the light beams of the twowavelengths introduced into each of the optical fibers is introducedinto an optical fiber, for example, an irradiation optical fiber 8-1 byan optical fiber coupler 7. The two-wavelength light beams from thelight modules are introduced into the irradiation optical fibers 8-1 to8-4, respectively, and irradiated onto four different irradiationpositions on the surface of a body 9 to be inspected out of the otherends of the irradiation optical fibers. Light reflected from the body tobe inspected is detected by detecting optical fibers 10-1 to 10-5arranged at five detecting positions. An end surface of each of theoptical fibers is softly in contact with the surface of the body 9 to beinspected, that is, the optical fiber is attached to the body 9 to beinspected using, for example, a probe described in Japanese PatentApplication Laid-Open No. 9-149903.

FIG. 24 is a view showing an example of a geographical arrangement ofthe irradiation positions 1 to 4 and the detecting positions 1 to 5 on asurface of the body 9 to be inspected. In the present embodiment, theirradiation position and the detecting position are alternativelyarranged on a square lattice. Assuming that the middle position betweenthe irradiation position and the detecting position adjacent to eachother is a measured position, number of measured positions, that is,number of measurement channels is 12 because there are 12 combinationsof the irradiation position and the detecting position adjacent to eachother. The arrangement of the light irradiation positions and thedetecting positions is described, for example, in Japanese PatentApplication Laid-Open No. 9-149903 and an article entitled“Near-infrared topographic measurement system: Imaging of absorberslocalized in a scattering medium” by Yuichi Yamashita et al., Review ofScientific Instrument, Volume 67, pages 730-732. It is reported, forexample, in an article entitled “Intracerebral penetration of infraredlight” by P. W. Mccormic et al., Journal of Neurosurgery, Volume 76,pages 315-318 that when the interval between the irradiation positionand the detecting position adjacent to each other is set to 3 cm, lightdetected at each of the detecting positions penetrates though the skinand the skull and has information.

From the above, by setting twelve measurement channels under thearrangement of the irradiation and the detecting positions, a cerebrumin an area of 6 cm×6 cm can be measured as a whole. Although the presentembodiment shows the case where the number of measurement channels is 12in order to simplify the explanation, the measurement area can be easilyexpanded by further increasing numbers of the light irradiationpositions and the light detecting positions arranged in a lattice tofurther increase number of measurement channels.

Referring to FIG. 1, the reflected light detected by each of thedetecting optical fibers 10-1 to 10-5 is detected on the detectingposition basis, that is, detected independently in the detecting opticalfiber corresponding to each of the detecting positions using the fivelight detectors, for example, using the photo-diodes 11-1 to 11-5. Thephoto-diode is preferably an avalanche photo-diode which can realizehigh sensitive light measurement. Further, a photo-multiplier tube maybe used as the light detector. After converting the light signal into anelectric signal by the photo-diode, a modulated signal corresponding toboth of the irradiation position and the wavelength is selectivelydetected by the lock-in amplifier module 12 composed of a plurality ofcircuits for selectively detecting a modulated signal, for example, aplurality of lock-in amplifiers. Although in the present embodiment thelock-in amplifiers are shown as the modulated signal detecting circuitscoping with the case of analogue modulation, digital filters or digitalprocessors for detecting the modulated signals are used in a case ofusing digital modulation.

FIG. 25 is a block diagram showing the construction of lock-in amplifiermodule of FIG. 1. Initially, explanation will be made on modulatedsignal separation of the detected signal detected by the photo-diode11-1 at the position 1 in FIG. 24. .At the “detecting position 1”, thelight irradiated at the “light irradiation position 1”, at the “lightirradiation position 2”, at the “light irradiation position 3” and atthe “light irradiation position 4” adjacent to the detecting position 1can be detected, and accordingly the “measured position 4”, the“measured position 6”, the “measured position 7” and the “measuredposition 9” in FIG. 24 are positions to be measured. Here, the detectedsignal detected by the photo-diode 11-1 at the “position 1” includeseight signal components having the modulation frequencies of f(1-a),f(1-b), f(2-a), f(2-b), f(3-a), f(3-b), f(4-a) and f(4-b) correspondingto the two-wavelength light each irradiated onto the “irradiationposition 1”, the “irradiation position 2”, the “irradiation position 3”and the “irradiation position 4”. The light signals containing the eightsignal components are introduced into the eight lock-in amplifiers 13-1to 13-8 through the 8 amplifiers 14-1 to 14-8. Modulation frequencysignals of f(1-a), f(1-b), f(2-a), f(2-b), f(3-a), f(3-b), f(4-a) andf(4-b) are given to the 8 lock-in amplifiers 13-1 to 13-8 as referencesignals, respectively. Therefore, the light signal components of 780 nmand 830 nm wavelengths irradiated onto the “irradiation position 1” areselectively separated by the lock-in amplifiers 13-1 and 13-2; the lightsignal components of 780 nm and 830 nm wavelengths irradiated onto the“irradiation position 2” are selectively separated by the lock-inamplifiers 13-3 and 13-4; the light signal components of 780 nm and 830nm wavelengths irradiated onto the “irradiation position 3” areselectively separated by the lock-in amplifiers 13-5 and 13-6; and thelight signal components of 780 nm and 830 nm wavelengths irradiated ontothe “irradiation position 4” are selectively separated by the lock-inamplifiers 13-7 and 13-8.

In regard to the detecting signals detected by the photo-diodes 11-2 to11-5 at the “detecting position 2”, at the “detecting position 3”, atthe “detecting position 4” and at the “detecting position 5”,respectively, the desired light signal components are similarlyselectively separated to be lock-in detected. That is, the light signaldetected by the photo-diode 11-2 at the “detecting position 2” isintroduced into the four lock-in amplifiers 13-9 to 13-12 through thefour amplifiers 14-9 to 14-12, and the light components of 780 nm and830 nm wavelengths irradiated at the “irradiation position 1” and thelight components of 780 nm and 830 nm wavelengths irradiated at the“irradiation position 2” each are selectively separated to be lock-indetected; the light signal detected by the photo-diode 11-3 at the“detecting position 3” is introduced into the four lock-in amplifiers13-13 to 13-16 through the four amplifiers 14-13 to 14-16, and the lightcomponents of 780 nm and 830 nm wavelengths irradiated at the“irradiation position 1” and the light components of 780 nm and 830 nmwavelengths irradiated at the “irradiation position 3” each areselectively separated to be lock-in detected; the light signal detectedby the photo-diode 11-4 at the “detecting position 4” is introduced intothe four lock-in amplifiers 13-14 to 13-20 through the four amplifiers14-14 to 14-20, and the light components of 780 nm and 830 nmwavelengths irradiated at the “irradiation position 3” and the lightcomponents of 780 nm and 830 nm wavelengths irradiated at the“irradiation position 4” each are selectively separated to be lock-indetected; and the light signal detected by the photo-diode 11-5 at the“detecting position 5” is introduced into the four lock-in amplifiers13-21 to 13-24 through the four amplifiers 14-21 to 14-24, and the lightcomponents of 780 nm and 830 nm wavelengths irradiated at the“irradiation position 2” and the light components of 780 nm and 830 nmwavelengths irradiated at the “irradiation position 4” each areselectively separated to be lock-in detected.

It can be understood from FIG. 24 that in the case where the detectingpositions are the “detecting position 2”; the detecting position 3”, the“detecting position 4” and the “detecting position 5”, the positions tobe measured are the “measured position 1” and the “measured position 3”,the “measured position 2” and the “measured position 5”, the “measuredposition 10”, and the “measured position 8” and the “measured position11”.

As described above, in the case where number of the wavelengths is twoand number of the measured positions is twelve, twenty-four of thelock-in amplifiers 13-1 to 13-24 in total are used in the lock-inamplifier module 12. Each of the analogue signals output from thelock-in amplifiers 13-1 to 13-24 (channel 1 to 24) is accumulated for apreset time by a sample hold circuit of the channel corresponding to thesample hold circuit module 16. After completion of the accumulation, theswitch (multiplexer) 17 is sequentially switched to convert the signalaccumulated in each of the sample hold circuits to a digital signal, forexample, by a 12-bit analogue/digital converter (A/D converter) 18, andthe converted signals in all of the channels are stored in a memory unitoutside a computer 19. Of course, the converted signals may be stored ina memory unit inside the computer 19.

The channel number corresponds to the address of the memory unit 15 witha one to one relation.

In a case of not using the sample hold circuit module 16, the switch 17is repetitively switched at high speed. The analogue signal of eachchannel is converted into a digital signal using the analogue/digitalconverter 18 every switching to be accumulated in the memory unit 20,and the digital signals acquired a preset number of times are averagedon the channel basis to be stored in the memory unit 20. This method canreduce noise of high frequency components.

Based on the data stored in the computer 19, change in the concentrationof oxygenated hemoglobin and change in the concentration of deoxygenatedhemoglobin associated with cerebral activity, and further change in theconcentration of total hemoglobin as the total concentration ofhemoglobin are calculated through the method described in, for example,Japanese Patent Application Laid-Open No. 9-19408 and in an articleentitled “Spatial and temporal analysis of human moter activity usingnoninverse NIR topography” by Atsushi Maki et al., Medical Physics,Volume 22, pages 1997-2005 (1995), and the result such as a topographyimage or the like is displayed on the display portion 20.

Referring to FIG. 1, the computer 19 may be a personal computer. Anoperating portion 22 is connected to the computer 19, and the operatingportion includes a keyboard, a mouse and so on for inputting andoutputting various kinds of information and for adding and deletingdata. FIG. 26 is a graph showing time variation of a measured signal 30at a detecting position and of a predicted no-load signal 31 obtainedfrom the measured signal. The graph is displayed on the display portion21, and the abscissa indicates measurement time and the ordinateindicates an amount of relative change in hemoglobin concentration, thatis, the amount corresponding to change in hemoglobin concentration at aspecific position in a cerebrum caused by motion of a specific positionof a body (for example, motion of a part of the body such as a finger orthe like). The predicted no-load signal 31 is obtained from the measuredsignal 30 by fitting an arbitrary function to the measured signal 31 inthe time before loading T1 and the time after applying load T3 exceptthe signals in the time applying load (loading time) Tt and the timeuntil the signal returns the original value (relaxation time) T2 throughthe least-squares method. In the present embodiment, the processing isperformed by using a secondary-order linear polynomial for the arbitraryfunction and by setting T1=40 seconds, T2=30 seconds and T3=30 seconds.

FIG. 27 shows an example of time variations of an amount of relativechange in concentrations of oxygenated hemoglobin and an amount ofrelative change in concentrations of deoxygenated hemoglobin at ameasurement position. The graph is displayed on the display portion 21.The abscissa indicates measurement time and the ordinate indicatesrelative amounts of change in the concentrations. The time illustratedby the hatched area is a load applying time (a period of moving a fingerof right hand). In regard to the relative amount of change shown in FIG.26, the relative amounts of changes in oxygenated hemoglobin and indeoxygenated hemoglobin (H_(b)O₂, H_(b)) associated with loadapplication is calculated based on the non-load signal 31 and thepredicted non-load signal 32 through a predetermined calculationprocessing.

Each of FIG. 28 and FIG. 29 shows a contour image (a topography image)produced from the time variation of the relative amount of change in aconcentration of oxygenated hemoglobin at each measurement positiondisplayed in the display portion 21 when motion of left-hand orright-hand fingers of a person to be inspected is used as load,respectively. The topography image is formed by calculating anintegrated value with time (an averaged value with time may beacceptable) of the signal of relative amount of change 32 in the loadapplying time (the hatched period in FIG. 27) by the processing portion19, and linearly interpolating between the measured positions in theX-axis direction and the Y-axis direction. As the topography image, amonochrome gray-scale image or a color identifying image may beacceptable instead of the contour image shown in FIG. 28 and FIG. 29. Itcan be understood from FIG. 28 and FIG. 29 that the oxygenatedhemoglobin concentration is clearly increased at a specific positionwhen right-hand finger is moved.

By displaying such information of spatial distribution as an image,recognition of the measured result can be made speedy and easy. Further,although the images shown in FIG. 28 and FIG. 29 are formed using thetime-integrated values of the relative amount of change in concentrationduring the load apply time period, a similar topography image can beformed using relative amounts of change in oxygenated hemoglobinconcentration at the measured positions every measuring time performedat a time. By displaying the plurality of formed topography images inorder of measured time or as a moving picture, the time variation of therelative amount of change in the oxygenated hemoglobin concentration canbe understood.

Further, by calculating a self-correlation function of the timevariation of the relative amount of change in oxygenated hemoglobinconcentration at an arbitrary one measured position and amutual-correlation function of the time variation of the relative amountof change in oxygenated hemoglobin concentration at one and the othermeasured positions, a topography image for each position can be alsoformed from the correlation functions. Since the correlation function ateach position is a function defined by shifting time by τ, a state ofpropagation of change in a dynamic blood state can be visualized byforming photography images from the values of the correlation functionsshifting by the same time of τ and displaying the photography images inorder of τ or as a moving picture. Although the description here is madeon the relative amount of change in oxygenated hemoglobin concentrationas the typical example, the relative amount of change in deoxygenatedhemoglobin concentration and the relative amount of change in the totalhemoglobin concentration calculated as the sum of the relative amountsof change in oxygenated and deoxygenated hemoglobin concentrations canbe similarly formed in the topography images.

FIG. 30 shows an example of a display superposing a topography image 34formed through the method described above on a cerebrum surface image 35of a person to be inspected. Since the topography image 34 is change ina dynamic blood state of a cerebrum changing in association with changein a biological function, it is preferable that the topography image isdisplayed by superposing on the cerebrum surface image. The cerebrumsurface image 35 is displayed by being measured by a three-dimensionalMRI or a three-dimensional X-ray CT. The topography image 34 is atopography image which is formed by converting the coordinate system sothat the coordinates of the measured positions are placed on the surfaceof the cerebrum, and then interpolating the values between the measuredpositions. When the formed topography image 34 is displayed bysuperposing on the cerebral surface image 35, the color of thesuperposed topography image 34 is made translucent so that the cerebralsurface image under the topography image 34 can be seen.

FIG. 2 is a flowchart showing an example of processing flow inaccordance with the present invention for measuring a body to beinspected using the optical measurement system shown in FIG. 1.Operation of the optical measurement system is sequentially performedwhile an operator is looking at the windows, shown in FIG. 3 to FIG. 22,displayed on a window display screen of the display portion 21.

As the operating system of the system is booted, an initial window forselecting main menu shown in FIG. 3 is displayed (S1). Referring to FIG.3, the processing proceeds to measurement processing when the button 301is selected, the processing proceeds to data analysis when the button302 is selected and the program is ended when the button 303 isselected.

Assuming now that the button 301 is selected, the initial window shownin FIG. 3 disappears, and the processing proceeds to the measurementprocessing to display a window for inputting conditions shown in FIG. 4is displayed in the middle of the display screen of the display portion21 (S2). In regard to FIG. 4, meaning and function of each part are asfollows.

401: A bar for inputting a title. In detail, a name of inspection to beperformed is input.

402: A part for displaying data and time, data and time as displayingthe window is displayed by default (automatically displayed numerals orcharacters).

403: A part for inputting a kind of stimulation (for example, fingermotion, writing, speaking, giving medication and so on). A list displaybutton (an inverted delta symbol button) is pushed and then desireditems are selected from pre-registered kinds in the list box. Theselected kinds are displayed by changing the back color or with reversedcharacters. The data can be added, deleted and replaced.

404: A kind of item selected in the stimulation input part can bedeleted by this button.

405: A part for selecting a measurement mode. The measurement mode isdetermined by number of measuring channels and number of surfaces to bemeasured. For example, in a case where number of measurement channels is1 and number of surfaces to be measured is 2, it is assumed thatmeasurement mode 1 is selected.

406: A part for freely writing memorandum.

407: A part for inputting name of a person to be inspected.

408: A part for inputting age of a person to be inspected.

409: A part for inputting sex of a person to be inspected.

410: A part for inputting a kind of a person to be inspected, that is, apatient or a healthy person.

411: A setting ending button.

412: A button for returning to the initial window.

After inputting and setting the above conditions, by pushing the button412, the window for inputting conditions disappears and a window fordisplaying gain adjusting underway shown in FIG. 5 is displayed in themiddle of the screen (S3) . This expresses that the measurement systemis under automatic gain adjusting, and after completion of theadjustment the window for displaying gain adjusting underway disappearsand a window for displaying measured positions is displayed in themiddle of the display screen (S4) . Essentially after now, this windowis always displayed at a position in the screen of the display portion21. By always displaying the window for displaying measured positions,it is possible to easily and speedily understand the correspondencebetween the many measured signals and the actual measured positions.There, the irradiation optical fibers 8-1 to 8-4 and the detectingoptical fibers 10-1 to 10-5 shown in FIG. 1 are generally fixed in ahelmet to be put on by the person to be inspected. Therefore, ifmeasuring channel numbers are indicated on the helmet to make thepositional relationship between the number shown by the referencecharacter 602 in FIG. 6, recognition of the operator is furtherassisted.

Referring to FIG. 6, the reference character 601 is a part fordisplaying the selected measuring mode, the displayed window fordisplaying measured positions corresponds to the measuring mode. Thereference character 602 is a part for displaying number of measuringchannels of the measured plane. The reference character 603 indicatesthe setting positions of the irradiation and the detecting opticalfibers, that is, the irradiation positions and the detecting positions.The reference character 604 indicates the measuring channel numbers, andthe measuring channel number is displayed in green color when theautomatic gain adjustment of the measuring channel is well performed.

When there exists at least one measuring channel which is failed in thegain adjustment, the measuring channel number of the measuring channelis displayed in red color. Further, in this case, a window for displayabnormality shown in FIG. 7 is displayed near the window for displayingmeasured positions shown in FIG. 6 (S5). The case where the gainadjustment is failed means that there is possibly a problem in ameasured position in the right-hand side or the left-hand side or theupper side or the down side of the channel displayed in red color. Sinceit is considered that there is a problem in setting of the optical fiberwhen the red-colored display appears, the optical fiber is required tobe reset. Therefore, after resetting the optical fiber, the referencecharacter 701 in FIG. 7 is used when the measurement is aborted byreturning to the window of FIG. 3 or FIG. 4. When the button 702 of FIG.7 is pushed, the window for display abnormality is deleted and thewindow for displaying gain adjusting underway is displayed to performthe automatic gain adjustment again. When there remains still anyabnormality after adjusting gain, the window for displaying gainadjusting underway shown in FIG. 5 is deleted, and the abnormalmeasuring channel in the window for displaying measured positions shownin FIG. 6 is displayed in red color, and the window for displayingabnormality shown in FIG. 7 is displayed near the window for displayingmeasured positions shown in FIG. 6. When no abnormality occurs, thewindow for displaying gain adjusting underway shown in FIG. 5 isdeleted, and all the measuring channels in the window for displayingmeasured positions shown in FIG. 6 are changed to green color, and awindow for forming a file shown in FIG. 8 is displayed.

In FIG. 7, the reference character 703 is a button which is pushed whenthe abnormality is neglected. When the button is pushed, the window forforming a file is displayed (S6) by neglecting the abnormal measuringchannel in the window for displaying measured positions shown in FIG. 6(remaining the red colored display as it is). The window for forming afile shown in FIG. 8 is displayed in the middle of the display screenregardless of presence and absence of abnormality, and the position ofthe window for displaying measured positions shown in FIG. 6 is moved toa lower left position in the display screen as the window for forming afile shown in FIG. 8 is displayed. By this display method, the operatorcan always watch the condition to be input.

In FIG. 8, meaning and function of each part are as follows.

801: A part for inputting a file name.

802: A part for displaying a list of all files existing in a hierarchywhich is selected by the button 804. For example, data names ofmeasurement previously performed are displayed in this part.

803: A part for displaying the present path.

804: A part for displaying a directory list (hierarchy list) .

805: A button for giving permission to proceed to measurement process.

806: A pushed button for canceling and returning to the window forinputting conditions of FIG. 4. When the button is pushed, the windowfor forming a file shown in FIG. 8 and the window for displayingmeasured positions shown in FIG. 6 are deleted, and the window forinputting conditions shown in FIG. 4 is displayed.

807: A button for displaying the window for creating directory, and thebutton is used when creating a new directory. When the button is pushed,the window for creating directory is displayed superposing on the windowfor forming a file shown in FIG. 8 in a slightly shifting state. At thattime, the window for creating directory shown in FIG. 9 can not beoperated.

808: A button for performing specifying a drive.

When the button 807 is pushed, the window for creating directory shownin FIG. 9 is displayed (S7). Referring to FIG. 9, the referencecharacter 901 is a part for inputting name of a directory to be created,the reference character 902 is a button for completing directorycreation, and the reference character 903 is a cancel button. When anyone of the buttons is pushed, the window for creating directory shown inFIG. 9 is deleted and the processing is returned to the window forforming a file shown in FIG. 8.

Referring to FIG. 8, when the button 805 is pushed, the window forforming a file shown in FIG. 8 is deleted, and a measurement windowshown in FIG. 10 is displayed an upper left portion of the displayscreen (S8), and a window or windows for displaying measurement datatime sequence shown in FIG. 14 is or are displayed in a large portion inthe right side of the display screen (S11). FIG. 8 is used forcontrolling execution of measurement. In regard to FIG. 10, meaning andfunction of each part are as follows.

1001: A button for selecting Info. When Info is selected, a window forselecting Condition or Tuneup as a sub-menu, as shown in FIG. 11. WhenCondition in sub-menu of FIG. 11 is selected, the window for inputtingcondition similar to FIG. 4 is displayed (S9). This is for checking thepresent status or inputting an additional condition. When Tuneup in thesub-menu of FIG. 11 is selected, a window for inputting measuringcondition and display condition shown in FIG. 12 is displayed (S12).When the cancel button is pushed in the step 9 or step 10, the windowfor inputting condition similar to FIG. 4 or the window for inputtingmeasuring condition and display condition shown in FIG. 12 is deleted,and the processing is returned to the measurement window of FIG. 10.

1002: When Option is selected by the button for selecting Option, Asub-menu window shown in FIG. 13 is displayed. Here, graph displayconditions for measurement underway, and conditions of a data backupinterval and signals output from the other measurement instruments to bedescribed later are input, but there is no need to input every timebecause there is a learning function to automatically reflecting valueswhich are set at the preceding measurement.

1003: A part for specifying and displaying a data acquisition timeinterval.

1004: A part for displaying number of data acquisition times (number ofsampling times).

1005: A part for displaying a measuring elapsing time.

1006: A part for displaying the next measurement state.

Run: measuring underway

Completion: normal completion of measurement

Overrun: abnormal completion of measurement due to overflow of A/Dconverter

Stop: abnormal completion of measurement due to the other cause

File error: error in measurement file writing

Backup file error: error in backup file writing

1007: A button for starting measurement. When the button is pushed,measurement is started and measurement data time sequence signal graphis displayed in each axis in FIG. 14 (S11) . The displayed graphexpresses a change ratio.

1008: A button for completing data acquisition.

1009: A button for completing measurement and inspection.

1010: A part for displaying an elapsing time after pushing Mark button1011: By this part, there is an advantage in that a stimulating timeperiod can be managed without using any stopwatch.

1011: The Mark button which is for inserting a mark of a vertical linein the graph of FIG. 14 during measurement. This mark is usually inputat starting and at completing stimulation as a reference for dataanalysis, but the mark may be arbitrarily input when an event requiringto record time occurs during measurement. When a mark input signal issupplied from an external device, a mark is displayed in the drawing ofFIG. 14 without pushing the button. Moreover, a sound may be generatedwhen the mark input signal is supplied.

In the window for inputting measuring condition and display conditionshown in FIG. 12, a measurement condition corresponding to a selectedmeasurement mode is displayed. The measurement condition expressescorrespondence to a measuring channel (measuring position), a channel ofA/D converter, a wavelength, a signal amplification and so on. Further,specifying of a channel to measure and specifying a channel to displaymay be possible. Furthermore, it is possible to instruct to inputanother signal into a vacant channel. In regard to FIG. 12, meaning andfunction of each part are as follows.

1201: There are tables showing the measurement conditions and thedisplay conditions for each wavelength using in the selected mode, and atable in regard to a wavelength to be displayed is selected using thistab.

1202: A part for specifying requirement of displaying a graph to displaythe graph. The word True in the column means displaying the graph, andthe word False means not displaying the graph. By pre-selecting graphsnot required to be display for individual channels (by clicking a box inthe Visible column, the selection is performed to change the back coloror to be inversely displayed), and then by specifying a False button of1212, the selected measurement channel is turned from True to False.

1203: A part for displaying a gain of the lock-in amplifier.

1204: A part for displaying a dynamic range of the A/D converter. In thecolumns of the parts 1203 and 1204, the values determined by theautomatic gain adjustment are displayed.

1205: A part for displaying wavelength.

1206: A part for displaying a kind of signal. The word Optical meansoptical measurement. For example, in a case where a brain wave signal ismeasured at a time using an additional channel (the addition can bespecified in the part 1208), the operator inputs EEG. The signals otherthan Optical can be separately processed during data analysis.

1207: A part for displaying a channel number of measurement.

1208: A part for specifying and displaying effectiveness (True) andineffectiveness (False) of the channel number of the A/D converter. Thespecifying method is similar to the case of the part 1202. When False isselected in a channel, measurement in the specified channel is notperformed.

1209: A window for inputting a character string or a number string in aposition selected in the parts 1202 to 1208.

1210: A part for changing the dynamic range of the A/D converter. Itbecome effective when the part 1204 is selected.

1211: A part for changing a gain of the lock-in amplifier. It becomeeffective when the part 1203 is selected.

1212: A part for switching True and False in the columns 1202 and 1208.

1213: A part for selecting a displayed measurement mode. The word Eachmeans that displayed tables are displayed by a plurality of tables foreach wavelength, and the word All means that all the measuring channelsare displayed by one table.

1214: A button for completing setting.

1215: A button for canceling setting.

According to the window of FIG. 12, checking and setting change can beeasily performed because the monitor of the measurement conditions (1203to 1208) and the conditions of graph display (1202) are shown on thesingle window. Further, a signal of another measurement instrument(apparatus) can be acquired using this window. Furthermore, the windowof FIG. 12 is only one window that the operator inputs used conditionsby selecting necessity of measuring input signals.

In a sub-menu window of Option in the measurement window of FIG. 10, thefollowing windows is displayed depending on which is selected. However,displays of Trigger Pulse and External Trigger to be selected areomitted in FIG. 13.

Graph: A window for inputting the display conditions of graph of FIG. 14(FIG. 15)

Backup: A window for inputting a file backup condition (FIG. 16)

Other CH: A window for input setting of the other measurement equipmentoutput signal (FIG. 17)

Trigger Pulse: A window for setting a rectangular wave output signal(FIG. 18)

External Trigger: A window for setting an external input triggersynchronous measurement condition (FIG. 20)

Measurement Parameter: A window for setting a measured data acquiringcondition (FIG. 21)

Prescan: A window for checking a measured signal (FIG. 22)

Position: A window for displaying measured positions (FIG. 6) (returningto the step S6)

In regard to FIGS. 15 to 18 and 20 to 22, meaning and function of eachpart are as follows.

FIG. 15 (the window for inputting the display conditions of graph ofFIG. 14) (S12)

1) A range of the X-axis is input. In order to input the range, thereare two input methods, that is, one is a method of inputting amagnification performed in 1501, and the other is a method of inputtinga displayed time performed in 1503.

1501: A button for selecting a display magnification inputting of theX-axis of graph.

1502: A part for inputting a display magnification of the X-axis ofgraph by a percentage. For example, in a case where the time period of3600 seconds is displayed when the magnification is 100%, the displayedtime period becomes wIthIn a range of 360 seconds if the magnificationis changed to 1000% In this case, when the time exceeds 360 seconds, thewindow is scrolled to the left-hand side. In detail, assuming data of362 seconds is acquired, the displayed range of the X-axis of the graphof FIG. 14 is from 2 seconds to 362 seconds.

1503: A button for selecting the displayed time inputting of the X-axisof the graph. When this button is selected, the button 1501 isautomatically changed to not selected. The button 1501 and the buttonare mutually exclusive.

1504: A part for inputting a displayed time period of the X-axis of thegraph.

1505: A part for displaying number of data kinds acquired within adisplayed time period specified in the part 1504.

2) A range of the Y-axis is input.

1506: A part for selecting a display magnification inputting of theY-axis of graph. The way of thinking is similar to that of the case ofselecting a display magnification inputting of the X-axis of graph.

3) The format of graph display of FIG. 14 is selected.

1507: A button for selecting displaying all the channels (all thechannels selected to display in FIG. 12) in order of the measuredchannel. When this button is selected, the windows shown in FIG. 14,number of which is equal to number of the wavelengths used in eachmeasurement channel in number (two wavelengths in this embodiment), aredisplayed so as to overlap with each other. In that case, the firstwindow shows signals of the first wavelength in order of the measuredchannel, and the second window shows signals of the second wavelength inorder of the measured channel. If the setting is particularly not made,Together is selected.

1509: A button for displaying all the channels within a single window.

1509: A button for separately displaying within a window for eachchannel. Further, there are two kinds of display methods as follows.

Title: Graphs are displayed by arranging in a matrix-shape.

Cascade: Graphs are displayed by superposing on another.

1510: A button for displaying only one specified channel (the channeldisplayed in FIG. 12 can be selected).

1511: A part for forcing not displaying the graphs.

1512: A part for completing the setting. By completing the setting, thewindow display is returned to the window display of FIG. 10.

1513: A part for canceling. In the case of canceling, the window displayis also returned to the window display of FIG. 10.

FIG. 16 (the window for inputting a file backup condition) (S13)

This window is for setting the condition of function of backup dataduring measurement at any time by assuming a case of a power outageduring measuring or a case where a file specified by the window forforming a file of FIG. 8 is damaged due to some causes.

1601: A part for specifying whether or not backup is necessary.

1602: A part for inputting a backup time interval.

1603: A part for inputting a backup file name by full-pass.

1604: A part for referring to a directory and a file. The window forforming a file of FIG. 8 is displayed, and the specified file name isentered to Backup File Name area.

1605: A button for completing the setting. By completing the setting,the window display is returned to the window display of FIG. 10.

1606: A button for canceling. In the case of canceling, the windowdisplay is also returned to the window display of FIG. 10.

FIG. 17 (The window for input setting of the other measurement equipmentoutput signal) (S14)

By this window, a signal output from another measurement instrument isacquired from data of a vacant A/D converter channel. A channel numberof the A/D converter used at acquiring the data, a name of kind of thesignal (EEG and so on) and a dynamic range of the A/D converter areselected.

1701: A part for displaying a channel number of a vacant A/D converterused for inputting. The vacant A/D converter having a least channelnumber is automatically allocated.

1702: A part for inputting a kind name of signal.

1703: A part for selecting a dynamic range of an A/D converter ofanother input.

1704: A button for completing the setting. By completing the setting,the window display is returned to the window display of FIG. 10.

1705: A button for canceling. In the case of canceling, the windowdisplay is also returned to the window display of FIG. 10.

FIG.18 (The window for setting a rectangular wave output signal (S15)

A rectangular wave voltage signal is periodically output from thepresent optical measurement system. By inputting this signal into theother measurement instruments (a brain wave meter and so on), themeasuring time can be strictly set in agreement between the instruments.The rectangular wave signal is output from, for example, a serial boardof a personal computer.

There are three kinds of the output rectangular wave signals, as shownin FIG. 19. The first kind is a rectangular wave signal which is outputonly at starting of measurement. The second kind is a rectangular wavesignal which is periodically output until the measurement is completed.The third kind is a rectangular wave signal which is output insynchronism with pushing of the mark button of FIG. 10. The condition ofthese three kinds of rectangular wave signals can be set by the windowof FIG. 18.

1801: Apart for selecting whether or not the rectangular wave output isnecessary.

1802: A part for selecting a terminal to output the rectangular wavesignal.

1803: A part for inputting a time width of the first kind of rectangularwave signal (refer to A of FIG. 19).

1804: A part for inputting number of repetitive times of the first kindof rectangular wave signal (refer to B of FIG. 19).

1805: A part for inputting number of repetitive times of the second kindof rectangular wave signal (refer to C of FIG. 19).

1806: A part for inputting a time width of the second kind ofrectangular wave signal (refer to D of FIG. 19).

1807: A part for inputting a time width of the third kind of rectangularwave signal (refer to E of FIG. 19).

1808: A button for completing the setting. By completing the setting,the window display is returned to the window display of FIG. 10.

1809: A button for canceling. In the case of canceling, the windowdisplay is also returned to the window display of FIG. 10.

FIG. 20 (The window for setting an external input trigger synchronousmeasurement condition) (S16)

This window is a window which is used when measurement is performed insynchronism with a trigger signal from the external. By performingsynchronous measurement, the time is completely in synchronism with theother measurement instrument and a stimulation apparatus.

2001: A part for specifying whether or not the external input triggersynchronous measurement is necessary.

2002: A part for inputting a channel number of the A/D converter usedfor the external input trigger signal.

2003: A part for inputting a measuring time to each trigger signal.

2004: A part for inputting a threshold value of a voltage value which isrecognized as the trigger signal.

2005: A button for completing the setting. By completing the setting,the window display is returned to the window display of FIG. 10.

2006: A button for canceling. In the case of canceling, the windowdisplay is also returned to the window display of FIG. 10.

FIG. 21 (the window for setting a measured data acquiring condition)(S17)

By this window, a channel operating frequency of the A/D converter(Burst Rate),a sampling frequency per one channel of the A/D converter(Conversion Rate), an average number of adding times of acquired data(number of Samples), an adding time of acquired data (Acquisition Time),a data acquisition time interval (Sampling Period: the same as the part1003 of FIG. 10) and a total measuring time can be set.

2101: A part for displaying and inputting Burst Rate.

2102: A part for displaying and inputting Conversion Rate.

2103: A part for displaying and inputting number of samples acquiringone sampling.

2104: A part for displaying a data acquisition time.

2105: A part for displaying and inputting a data acquisition timeinterval.

2106: A part for displaying and inputting a measurement time.

2107: A button for completing the setting. By completing the setting,the window display is returned to the window display of FIG. 10.

2108: A button for canceling. In the case of canceling, the windowdisplay is also returned to the window display of FIG. 10.

FIG. 22 (The window for checking a measured signal) (S18)

This window is used for that the operator checks the state of signals byperforming pre-measurement in prior to starting the actual measurement,if necessary. A value of signal displayed in the graph is expressed by avoltage value.

2201: A part for displaying a data acquisition time interval.

2202: A part for displaying number of data acquisition times (number ofsampling times).

2203: A part for displaying a measuring elapsing time.

2204: A part for displaying a measuring state (refer to FIG. 10).

2205: Apart for specifying a magnification of the X-axis of the graph(refer to FIG. 15).

2206: A part for displaying the result of pre-measurement by numericalvalues for each channel.

2207: A button for starting of checking output signals. When this buttonis pushed, the measured signals are displayed in a single window or aplurality of windows shown in FIG. 14 corresponding to the form of thegraph set by the window shown in FIG. 15.

2208: A button for aborting measurement.

2209: A button for completing the pre-measurement. By pushing thisbutton, the display window is returned to the 20 display window of FIG.10.

By the embodiment described above, an operator, even if not skilled, canperform input work speedily and without error. Further, there areprovided the option functions which can be set by an operator.

According to the present invention, it is possible to provide an opticalmeasurement system and an optical measurement method which is suitablefor optically measuring a body to be inspected and easily obtaining animage of a desired item based on information obtained by themeasurement.

Further, according to the present invention, an operator, even if notskilled, can perform input work speedily and without error. Accordingly,the operator can perform the optical measurement operation even if he isnot understand the operating manual very well.

Furthermore, according to the present invention, it is possible tounderstand a state of change in a body to be inspected, for example, anactivation state of cerebral oxygen metabolism with high accuracy.

1. An optical measurement system comprising: a plurality of lightsources for irradiating light on a biological body; a plurality of lightdetectors for detecting light which is irradiated from said lightsources and propagate through said biological body; a computer forcalculating the concentration of oxygenated hemoglobin and deoxygenatedhemoglobin; and a display for displaying a calculated results of saidcomputer; wherein said display displays a window for showingcorrespondence between a measuring channels and a channels of A/Dconverter, where which measuring channels to use for measuring or whichmeasuring channels to display may be specified.
 2. An opticalmeasurement system according to claim 1, wherein said window has a partfor changing a dynamic range of said A/D converter, or a part forchanging a gain of a lock-in amplifier.
 3. An optical measurement systemaccording to claim 1, wherein said window has a part for selectingwhether to acquire a signal of another measurement instrument.